GOME and SCIAMACHY solar measurements: Solar spectral irradiance and Mg II solar activity proxy indicator .

GOME (Global Ozone Monitoring Experiment, 1995-present) and SCIAMACHY (SCanning Imaging Absorption Spectrometer for Atmospheric CHartographY, 2002-present) provide solar observations in the visible and near UV since 1995. SCIAMACHY also measures in the near IR with some gaps up to 2380 nm. The solar spectral irradiance measured by SCIAMACHY is compared with results from other data sources such as SIM, SOLSPEC, SOLSTICE, and SUSIM and is generally in good agreement within 2 to 3% in most cases. The Mg II index is derived from daily solar observations in the near UV spectral region which provides a good measure of the solar EUV variability. For the understanding of the solar-terrestrial climate interaction the establishment of a long Mg II time series spanning several decades is important. A continuous solar Mg II index from 1995 to 2005 composed from GOME and SCIAMACHY solar measurements is presented and compared with Mg II data available from NOAA.